This proposal seeks support for a Research Scientist Award (KO5). The support would allow the candidate to continue full-time involvement in a program of psychiatric epidemiologic research developed over the past decade with the support of an RSDA (KO2) award. This work includes several components which together require a full-time research commitment. These different components are linked by a common focus on psychosocial causes of first onset and course of psychiatric disorders. (l) The candidate would continue a project supported by an NIMH MERIT award to study the mental health of married couples with a particular focus on dyadic adjustment to stress and sex differences in psychiatric disorders. (2) He would also continue a collaborative series of studies of gene-environment interactions for common psychiatric disorders based on general population studies of identical and nonidentical twins. (3) He would continue as the PI of the National Comorbidity Survey (NCS), the first survey in the U.S. to administer a structured psychiatric diagnostic interview to a nationally representative sample of the general population. As part of the NCS activities, he would also continue to participate in a series of methodological studies aimed at developing short-form structured measures of psychiatric disorders that can be used in large ongoing national health surveys, including the U.S. National Health Interview Survey and the SAMSHA National Household Survey of Drug Abuse. In addition to his research activities, the candidate would continue serving as the PI of an NIMH interdisciplinary Training Program and as a mentor to a number of young scholars affiliated with that program.